Self-assembly of dendronized triphenylenes into helical pyramidal columns and chiral spheres.

The synthesis and structural and retrostructural analyses of a library containing 10 triphenylenes functionalized with self-assembling benzyl ether and phenyl propyl ether dendrons are reported. These dendronized triphenylenes adopt a crown rather than discotic conformation. Their crown conformation mediates the self-assembly of the discotic triphenylene unit in helical pyramidal columns and in chiral spheres. The chiral spheres are generated from short segments of helical pyramidal columns that are spherically distorted. Therefore, the chirality of the sphere is determined by a short helical pyramidal column that represents the inner part of the supramolecular sphere. Both the helical pyramidal columns and the chiral spheres represent supramolecular architectures that were self-assembled for the first time from discotic molecules. The helical pyramidal columns self-organize in various hexagonal and rectangular lattices, while the chiral spheres self-organize into cubic and tetragonal periodic arrays and into a quasiperiodic 12-fold liquid quasicrystal. The helical sense of the helical pyramidal columns and of helical spheres is selected by a stereocenter that can be incorporated either in the alkyl groups of the dendron or in the triphenylene part of the dendritic crown via donor-acceptor interactions. The self-assembly process of the dendronized triphenylene donor can be programmed by a new supramolecular "polymer effect" generated by donor-acceptor interactions.